U.S. Pat. No. 4 139 458 describes a planar centrifugal chromatography device in which a rotor constructed as a flat disk and made of glass is arranged within a chamber which is inclined to the horizontal. The adsorbing medium is arranged on the upper side of the rotor. An inner wall of the chamber, which is inclined toward the axis of the rotor at an angle of less than 90.degree. with respect to the upper side of the rotor, forms the collecting device. The solvent is introduced onto the upper surface of the adsorbing medium near the shaft of the rotor. The solvent flows through the adsorbing medium under the action of centrifugal force, which causes the chromatographical separation. The solvent exits from the adsorbing medium, together with the separated substance, at the edge of the circular glass disk and moves, due to the centrifugal force, into the collecting device which is constructed in the stationary chamber. The solvent flows, under the action of gravity, to the lowermost point of the inclined chamber, where it is removed from the device through an output opening.
A disadvantage of this solution is that the solvent, together with the separated substances contained in the solvent, moves from the higher points of the chamber-- due to the relatively large distance and the weak driving force of gravity -- only slowly into the output opening. The solvent particles which move into the collecting channel near the output opening leave the device more quickly. Thus, there exists the danger of remixing between the already separated particles, which causes the separation accomplished in the adsorbing medium to become substantially worse.
A further disadvantage of the known device is that the great turbulence which occurs due to the rotor, which rotates in the vapor space, does not permit the construction of a vapor space with a defined composition. This has the result that a part of the solvent does not flow through the adsorbing medium, but instead evaporates and is removed -- not fulfilling its task. This fact reduces the repeatability and efficiency of the separation. Because of these deficiencies, it is not possible to carry out analytic (non preparatory) chromatography with the known device.
A further disadvantage in the design according to U.S. Pat. No. 4 139 458 is that the adsorbing medium is glued on the glass plate which forms the rotor, or is secured thereon. Thus, only an adhesive adsorbing medium can be used.
Tests have been made to overcome this disadvantage, namely with a disk in which the adsorbing medium is arranged between two parallel circular glass plates. (See the device of Hitachi Corp.) The disadvantage of this solution is that a cross section of the adsorbing medium which is vertical with respect to the radius is not constant, that is, the force due to inertia changes with the distance from the centerpoint, which results in a strip enlargement.
In another known device (PCT WO 85/04594 and HRC & CC, Edition 8/1985/Pages 53, 132), the solvent is applied to the center part of a rotatable rotor inclined at an angle to the horizontal with the help of a feed device which is movable and adjustable between the centerpoint and the edge of the rotor. After the chromatographic separation is finished, the solvent is removed with the help of an annular stationary collecting device. In this solution, there again exists the danger of remixing, that is, the efficiency of the separation accomplished in the adsorbing medium is through this discharge substantially reduced.
A purpose of the invention is to create a planar centrifugal chromatography device in which the discharge of the solvent can be accomplished quickly and without any danger of remixing.